Download transcription and translation

DNA -> RNA -> protein ->
trait
1. DNA, RNA structure
2. Transcription, translation
3. Mutations
Different chapters in the “Book
of You”
• Almost all of your cells
have the same DNA
(except red blood cells
and sperm/egg cells)
• But they express
different genes
(sections of DNA),
producing different
proteins, making
different traits.
Q: How do you fit 1 meter of
DNA into a nucleus?
• A: you coil it up using histone proteins
Nucleotides have 3 parts: Sugar, Phosphate,
Nitrogenous Base
• Sugar + phosphate = the backbone or sides of
the ladder
• Nitrogenous base = Adenine, Guanine,
Cytosine, Thymine, or Uracil
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De-oxy-ribo-nucleic Acid = DNA
• DNA is a nucleic acid
• Deoxyribos sugar in the
sugar-phosphate
backbone
• Nucleotides= A, T, C, G
• Double stranded
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• RNA is also a nucleic acid
– different sugar: Ribos, instead of Deoxiribos
– Nucleotides: A, U, C, G (no T)
– Single strand instead of double
Nitrogenous base
(A, G, C, or U)
Phosphate
group
Uracil (U)
Sugar
(ribose)
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Figure 10.2C, D
• DNA -> RNA -> protein -> trait
– Transcription: when the messenger RNA
(mRNA) makes a copy of the DNA. This
happens in the nucleus
DNA
TRANSCRIPTION
RNA
TRANSLATION
Protein
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Transcription produces genetic messages in the
form of mRNA
RNA
polymerase
RNA nucleotide
Direction of
transcription
Template
strand of DNA
Figure 10.9A
Newly made RNA
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• In transcription:
1. RNA polymerase
attaches to the promoter
region and unzips the
DNA helix,
2. RNA nucleotides line
up along one strand of
DNA,
3. When the
polymerase reaches the
terminator, it releases
and DNA strands rejoin
Figure 10.9B
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RNA polymerase
DNA of gene
Promoter
DNA
Initiation
Elongation
Terminator
DNA
Area shown
in Figure 10.9A
Termination
Growing
RNA
Completed RNA
RNA
polymerase
Fig. 17-7a-1
Promoter
Transcription unit
5
3
Start point
RNA polymerase
DNA
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3
5
Fig. 17-7a-2
Promoter
Transcription unit
5
3
Start point
RNA polymerase
3
5
DNA
1
Initiation
5
3
Unwound
DNA
3
5
RNA
transcript
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Template strand
of DNA
Fig. 17-7a-3
Promoter
Transcription unit
5
3
Start point
RNA polymerase
3
5
DNA
1
Initiation
5
3
3
5
Unwound
DNA
RNA
transcript
Template strand
of DNA
2 Elongation
Rewound
DNA
5
3
3
5
RNA
transcript
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3
5
Fig. 17-7a-4
Promoter
Transcription unit
5
3
Start point
RNA polymerase
3
5
DNA
1
Initiation
5
3
3
5
Unwound
DNA
RNA
transcript
Template strand
of DNA
2 Elongation
Rewound
DNA
5
3
3
5
3
5
RNA
transcript
3 Termination
5
3
3
5
5
Completed RNA transcript
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3
Transcription: happens in the nucleus, makes an
mRNA strand.
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• DNA -> RNA -> protein -> trait
– Translation: when the mRNA is “read” by the
ribosome in the cytoplasm, which produces a
protein.
DNA
TRANSCRIPTION
RNA
TRANSLATION
Protein
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Translation of nucleic acids into amino acids
• Codons: groups of three mRNA letters
– The codon determines which amino acid is used.
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Amino acid chart
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Translation
1. mRNA goes into the
cytoplasm and
attaches to a
ribosome.
2. The ribosome “reads”
the three-letter code
on the mRNA.
3. The t-RNA brings the
correct amino acid to
join the chain.
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Translation: happens in the cytoplasm. The
ribosome “reads” the mRNA and builds the
chain of amino acids to create a protein.
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Fig. 17-13
Amino
acids
Polypeptide
Ribosome
tRNA with
amino acid
attached
tRNA
Anticodon
Codons
5
mRNA
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3
b
a
Red object = ?
Yellow string = ?
Green string = ?
What molecules are present
in this photo?
Types of RNA
Location
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Function
Mutations that matter:
Change DNA  Change RNA  Change Protein
 Change Trait
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What are Mutations?
• Mutations are any change in the DNA
• Happens because a mistake is made during
the replicating of DNA (mitosis).
• Can be caused by chemicals, UV light, X-rays
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